LONGECITY

Like many people, I intermittently take vitamin D3 supplements, because I'm likely not getting enough from food and sunlight alone. Since I take vitamin D3 supplements intermittently, I've noticed a peculiar pattern: whenever I supplement with vitamin D3, my sex drive hits rock bottom. I get urination problems, too. Sometimes, I also get headaches, although I'm not 100% sure if this is attributable to the vitamin D3. Even three or four days of supplementation is enough to trigger these side effects. Whenever I stop with the vitamin D3, I return back to normal after a week or so.

I'm not overdosing. I always use normal amounts of vitamin D3. Never more than 2500 IU daily, but most of the time just 2000 IU. And even as little as 800 IU gives the exact same side effects. I've all but ruled out contamination of my supplements. I use Jarrow Formulas, which seems like a reputable brand. Moreover, I've gone through multiple batches, which further reduces the likelihood of contamination. After all, even if we assume that Jarrow Formulas occasionaly screws up, they're unlikely to screw up all the time.

Could this be a sign that I'm extraordinarily deficient? Maybe my body upregulated vitamin D receptors, after years of deficiency? Or maybe it has something to do with my mineral balance? Calcium or magnesium deficiency? What about the hormonal effects of vitamin D? It has an effect on testosterone and estrogen levels, right? Could the vitamin D effect my neurotransmitters? I've read it supports dopamine and serotonin production. I'm just throwing all these things out, I'm really no expert.

So any idea what could be causing this? It's very weird that even 800 IU has such a profound negative effect on me. Other people have similar experiences?

Vitamin D raises free testosterone levels as well as dopamine and serotonin synthesis rates. 

Specifically Vitamin D acts as a neurosteroid to stimulate the expression of tryptophan hydroxylase and tyrosine hydroxylase (the rate limiting enzymes for NT synthesis).

Vitamin D may in theory, raise both DHT and estradiol by means of raising free T, however, Vitamin D ALSO mildly inhibits aromatase - lessening the conversion (but mildly) of testosterone to estrogen.

Vitamin D also interacts with MANY other enzymes and proteins, and also stimulates thyroid hormone production.